Exemplary embodiments of the present invention relate to a semiconductor integrated circuit, and more particularly, to a semiconductor memory device and a driving method thereof.
A dynamic random access memory (DRAM), which is widely used among memory devices, stores data into a unit cell including one transistor and one capacitor. In order to store a larger amount of data in a semiconductor memory device, a larger number of cells are integrated in the semiconductor memory device. Cells of a memory device may be designed and fabricated in the smallest size within the bounds of related technologies.
Accordingly, a data signal stored in a memory cell may be so weak that it may not be directly outputted to the outside of the memory device. Therefore, semiconductor memory devices may include an amplification circuit configured to amplify a data signal stored in a memory cell. In general, the amplification circuit provided in semiconductor memory devices is referred to as a sense amplifier. Semiconductor memory devices include at least two-stage sense amplifiers to sufficiently amplify a data signal such that the data signal may be stably outputted to the outside of the semiconductor memory devices.
To reduce the number of sense amplifiers provided in the semiconductor memory devices, one sense amplifier is commonly disposed in neighboring cell blocks and a selected cell block of the neighboring cell blocks may be connected to the sense amplifier. In order to accomplish this, a switch connecting the sense amplifier and the cell blocks is provided. Furthermore, there is demand for a control circuit controlling the switch.
Meanwhile, a low-level voltage is used as a driving voltage to reduce power consumption in semiconductor memory devices. Accordingly, it may take a relatively large amount of time for the sense amplifier to sense and amplify a data signal using the low-level voltage. To address this concern, a technique which provides a relatively high-level voltage as the driving voltage at the moment the sense amplifier senses a data signal may be applied to drive semiconductor memory devices. This is referred to as an overdriving of the semiconductor memory device.
The effectiveness of the sense amplifier in amplifying the data signal is influential in the operation characteristics of semiconductor memory devices. Therefore, it is desired to effectively drive the sense amplifier.